Compressor Flow Passage Layout for Uniform Refrigerant Mixing
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Solution Overview
Problem
In multi-stage centrifugal refrigerant compressors, uneven distribution of refrigerant pressure, temperature, and density due to non-uniform mixing of inter-stage pressure refrigerant with main-flow refrigerant reduces aerodynamic efficiency, and increasing the length of the flow passage to address this issue compromises shaft rigidity and increases material costs.
Innovation Solution
A two-way flow passage structure with diverging outlets and side discharge passages is introduced, allowing inter-stage pressure refrigerant to be uniformly mixed with main-flow refrigerant in the return channel bend, reducing flow loss and compressor length, and enhancing shaft rigidity by shortening the cantilever length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the length of the main flow passage between the first and second stage centrifugal compressor impellers is increased to improve refrigerant mixing uniformity, then the mixing uniformity is improved, but the shaft rigidity is reduced and flow loss increases
Solution Approach 1:
The flow passage is segmented into multiple discharge outlets (first side discharge flow passage and second side discharge flow passage) positioned at different locations around the return channel bend. This segmentation allows refrigerant to be injected at multiple points, achieving uniform mixing without extending the overall passage length, thereby maintaining shaft rigidity while improving mixing uniformity.
Solution Approach 2:
Instead of extending the flow passage in the axial direction (one dimension), the invention utilizes the radial and circumferential dimensions by positioning discharge outlets at different angular positions around the return channel bend. This multi-dimensional approach achieves uniform refrigerant distribution without increasing the axial length, thus avoiding shaft rigidity reduction.
2Stability of the object's composition
If the length of the main flow passage between the first and second stage centrifugal compressor impellers is increased to improve refrigerant mixing uniformity, then the mixing uniformity is improved, but the flow loss increases
Solution Approach 1:
The flow passage is divided into multiple discharge outlets positioned at different locations around the return channel bend. This segmentation enables refrigerant injection at multiple strategic points, achieving uniform mixing within a shorter overall passage length, thereby reducing flow loss while maintaining mixing uniformity.
Solution Approach 2:
Refrigerant is injected into the return channel bend at multiple predetermined locations before entering the second stage impeller. This preliminary distribution ensures uniform mixing occurs early in the passage, allowing the use of a shorter flow passage and reducing cumulative flow loss while achieving the desired mixing uniformity.
3Length of stationary object
If the length of the cantilever L1 of the high-speed cantilever shaft is increased to accommodate a longer flow passage, then the flow passage length is increased, but the shaft rigidity is reduced and material cost increases
Solution Approach 1:
The invention transitions from extending the flow passage axially (increasing cantilever length) to utilizing radial and circumferential space by positioning discharge outlets at different angular positions around the return channel bend. This dimensional shift achieves the required mixing without increasing axial length, thereby maintaining shaft rigidity and reducing material cost.
Solution Approach 2:
The flow passage is segmented into multiple short discharge outlets positioned around the return channel bend rather than using a single long passage. This segmentation achieves uniform refrigerant distribution within a compact axial space, avoiding the need for a longer cantilever shaft and preserving shaft rigidity while reducing material cost.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution improves refrigerant mixing, increases compression efficiency, reduces flow loss, and allows for a more compact and cost-effective compressor design with increased shaft rigidity.
Implementation Method 1
the refrigerant diverged from the two-way flow passage can be discharged into the return channel bend and uniformly mixed with the refrigerant in the return channel bend
Data Source
AI summary
A flow passage structure can be disposed in a multi-stage centrifugal refrigerant compressor having a deswirl vane and a return channel bend. The flow passage structure includes a two-way flow passage having a first outlet and a second outlet, for diverging externally injected refrigerant; a first side discharge flow passage connected to the first outlet of the two-way flow passage and having a first side outlet disposed below the deswirl vane, such that the diverged refrigerant can be discharged into the return channel bend and uniformly mixed with the refrigerant in the return channel bend; and a second side discharge flow passage connected to the second outlet of the two-way flow passage and having a second side outlet disposed below the deswirl, vane, such that the diverged refrigerant can be injected into the return channel bend and uniformly mixed with the refrigerant in the return channel bend.